U.S. Pat. No. 4,063,064 issued on Dec. 13, 1977 to Richard, J. Saunders and Wayne S. Mefferd, and U.S. Pat. No. 4,088,864 issued on May 9, 1978 to Felix Theeuwes, Richard J. Saunders and Wayne S. Mefferd, disclose a tablet treating machine with a single rotating wheel for transporting tablets up from a tablet reservoir to a laser treatment station.
The wheel is inclined and has a set of slots each of which carries a single tablet. The slots have a bottom surface, two side walls, and a back wall formed on the inclined side of the wheel for cradling the tablet during transport. The laser beam accesses the tablet on the front exposed side for drilling a drug release port therein. The tablets may be drilled on one side only. The backside of each tablet rests against the back wall of the slot and is inaccessible to the laser beam.
The energy of the laser pulse in these machines requires about five milliseconds to form the release port in the tablet. A tracking mirror is employed to keep the laser beam trained on the tablet during the laser pulse period. Synchronism between the laser pulse and the sequence of tablets is maintained manually by an operator who monitors the operation of the machine. The shape and size of the laser beam is controlled by laser optics.